How can i apply gobos to a spotlight to make it look like a real life moving head light?
What worked for me (for the same exact purpose) was to use either geometry (as @RBlong2us suggested - with the wanted shape made firstly as a vector image and then extruded in Blnder) or even simpler (as is in my example) by using a plane and put it in front of my spotlight (as a real gobo would be) with an alpha texture. In order to make this working you should take care of the blend Mode and Shadow Mode of the plane's material. You may take a look on the image below.